Because women's breasts have been so sexualized and America's got a seriously problematic and puritanical view on women's bodies, the image of a mother naturally breastfeeding her child upsets some people.
But even the stodgiest of prudes who can't stand the sight of moms providing their babies with sustenance, can't deny how incredible breastfeeding is. Yes, it's an act pretty much all mammals are capable of, but it's still amazing that a baby can grow and live purely off of milk that a woman's body naturally produces.
It's even more amazing when women don't allow the fact that they're "a mom now" get in the way of their other interests, pursuits, or activities. And Serah Small is one such mom.